Tyrannise proactive person outside coal pit (8)
I believe the answer is:
domineer
'tyrannise' is the definition.
(I know that tyrannise can be written as domineer)
'proactive person outside coal pit' is the wordplay.
I cannot quite see how this works, but
'person' could be 'dominee' (dominee is a kind of person) and 'dominee' is present in the answer.
A single letter 'r' remains which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for domineer that I've seen before include "Tyrannise" , "Deem iron to be changed to overbear" , "Boss around" , "Tyrrannise" , "Behave imperiously" .)